﻿#pragma once
#include<iostream>
#include<assert.h>
using namespace std;


template<class K, class V>
struct AVLTreeNode
{
	pair<K, V> _kv;
	AVLTreeNode<K, V>* _left;
	AVLTreeNode<K, V>* _right;
	AVLTreeNode<K, V>* _parent;
	int _bf; // balance factor

	AVLTreeNode(const pair<K, V>& kv)
		:_kv(kv)
		, _left(nullptr)
		, _right(nullptr)
		, _parent(nullptr)
		, _bf(0)
	{}
};

template<class K, class V>
class AVLTree
{
	typedef AVLTreeNode<K, V> Node;
public:
	AVLTree() = default;

	AVLTree(const AVLTree<K, V>& t)
	{
		_root = Copy(t._root);
	}

	AVLTree<K, V>& operator=(AVLTree<K, V> t)
	{
		swap(_root, t._root);
		return *this;
	}

	~AVLTree()
	{
		Destroy(_root);
		_root = nullptr;
	}

	bool Insert(const pair<K, V>& kv)
	{
		if (_root == nullptr)
		{
			_root = new Node(kv);
			return true;
		}

		Node* parent = nullptr;
		Node* cur = _root;
		while (cur)
		{
			if (cur->_kv.first < kv.first)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (cur->_kv.first > kv.first)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				return false;
			}
		}

		cur = new Node(kv);
		if (parent->_kv.first < kv.first)
		{
			parent->_right = cur;
		}
		else
		{
			parent->_left = cur;
		}
		cur->_parent = parent;

		// 更新平衡因子
		while (parent)
		{
			if (cur == parent->_left)
				parent->_bf--;
			else
				parent->_bf++;

			if (parent->_bf == 0)
			{
				break;
			}
			else if (parent->_bf == 1 || parent->_bf == -1)
			{
				// 继续往上更新
				cur = parent;
				parent = parent->_parent;
			}
			else if (parent->_bf == 2 || parent->_bf == -2)
			{
				// 不平衡了，旋转处理
				if (parent->_bf == 2 && cur->_bf == 1)
					RotateL(parent);
				else if (parent->_bf == -2 && cur->_bf == -1)
					RotateL(parent);
				else if (parent->_bf == 2 && cur->_bf == -1)
					RotateRL(parent);
				else
					RotateLR(parent);
			}
			else
			{
				assert(false);
			}
		}

		return true;
	}

	Node* Find(const K& key)
	{
		Node* cur = _root;
		while (cur)
		{
			if (cur->_key < key)
			{
				cur = cur->_right;
			}
			else if (cur->_key > key)
			{
				cur = cur->_left;
			}
			else
			{
				return cur;
			}
		}

		return nullptr;
	}

	void InOrder()
	{
		_InOrder(_root);
		cout << endl;
	}
private:

	// 左单旋
	void  RotateL(Node* parent)
	{
		Node* subR = parent->_right;
		Node* subRL = subR->_left;

		parent->_right = subRL;
		if (subRL)
			subRL->_parent = parent; 

		Node* parentParent = parent->_parent;

		subR->_left = parent;
		parent->_parent = subR;

		if (parentParent == nullptr)
		{
			_root = subR;
			subR->_parent = nullptr;
		}
		else
		{
			if (parent == parenrParent->_left)
				parentParent->_left = subR;
			else
				parenrParent->_right = subR;

			subR->_parent = parentParent;
		}

		parenr->_bf = subR->_bf = 0;
	}


	// 右单旋
	void RotateR(Node* parent)
	{
		Node* subL = parent->_left;
		Node* subLR = subL->_right;

		Node* parentParent = parent->_parent; 

		subL->_right = parent;
		if (subLR)
			subLR->_parent = parent;
		
		parent->_left = subL;
		parent->_parent = subL;

		if (parentParent == nullptr) 
		{
			_root = subL;
			subL->_parent = nullptr;
		}
		else
		{
			if (parent == parentParent->_left)
				parentParent->_left = cur;
			else
				parentParent->_right = cur;

			subL->_parent = parentParent;
		}
		subL->_bf = parent->_bf = 0;
	}

	void RotateRL(Node* parent)
	{
		Node* subR = parent->_right;
		Node* subRL = subR->_left;
		int bf = subRL->_bf;

		RotateR(parent->_right);
		RotateL(parent);

		if (bf == 0)
			subR->_bf = subRL->_bf = parent->_bf = 0;
		else if (bf == 1) // subRL右边插入
		{
			subR->_bf = subRL->_bf = 0;
			parent->_bf = -1;
		}
		else if (bf == -1) // subRL左边插入
		{
			subR->_bf = 1;
			subRL->_bf = parent->_bf = 0;
		}
		else
			assert(false);
	}

	void RotateLR(Node* parent)
	{
		Node* subL = parent->_left;
		Node* subLR = subL->_right;
		int bf = subLR->_bf;

		RotateL(subL);
		RotateR(parent);

		if (bf == 0)
			parent->_bf = subL->_bf = subLR->_bf = 0;
		else if (bf == 1)
		{
			parent->_bf = -1;
			subL->_bf = subLR->_bf = 0;
		}
		else if (bf == -1)
		{
			subL->_bf = 1;
			parent->_bf = subLR->_bf = 0;
		}
		else
			assert(false);
	}

	void Destroy(Node* root) 
	{
		if (root == nullptr)
			return;

		Destroy(root->_left);
		Destroy(root->_right);
		delete root;
	}

	Node* Copy(Node* root)
	{
		if (root == nullptr)
			return nullptr;

		Node* newRoot = new Node(root->_key, root->_value);
		newRoot->_left = Copy(root->_left);
		newRoot->_right = Copy(root->_right);

		return newRoot;
	}

	void _InOrder(Node* root)
	{
		if (root == nullptr)
		{
			return;
		}

		_InOrder(root->_left);
		cout << root->_kv.first << ":" << root->_kv.second << endl;
		_InOrder(root->_right);
	}

	/// //////////////////////////////////////////////////////////////////////////////////////
/// 测试是否为AVL树

public:
	bool IsBalanceTree()
	{
		return _IsBalanceTree(_root);
	}

private:
	int _Height(Node* root)
	{
		if (root == nullptr)
			return 0;

		int leftHeight = _Height(root->_left);
		int rightHeight = _Height(root->_right);

		return leftHeight > rightHeight ? leftHeight + 1 : rightHeight + 1;
	}

	bool _IsBalanceTree(Node* root)
	{
		if (nullptr == root)
			return true;

		int leftHeight = _Height(root->_left);
		int rightHeight = _Height(root->_right);
		int diff = rightHeight - leftHeight;

		if (abs(diff) >= 2)
		{
			cout << root->_kv.first << "高度差异常" << endl;
			return false;
		}

		if (root->_bf != diff)
		{
			cout << root->_kv.first << "平衡因子异常" << endl;
			return false;
		}

		return _IsBalanceTree(root->_left) && _IsBalanceTree(root->_right);
	}

private:
	Node* _root = nullptr;
};